The invention relates to sustained-release matrices.
Most humans suffer from tooth decay and/or periodontal disease caused by bacteria in the mouth. As a result, decreasing the number of bacteria in the mouth has long been the target of persons working in the health care field. The most common way of minimizing the number of bacteria is to brush and floss the teeth regularly, and to visit a dental hygienist to have the teeth and gums cleaned thoroughly. Another prior approach is oral rinsing, including with a solution containing a known anti-microbial agent like chlorhexidine digluconate.
After a toothbrush has been used, there are a large number of bacteria clinging to the bristles, even after the brush has been rinsed. This, of course, is undesirable, and these bacteria typically will multiply on the bristles between uses. To counter this problem, self-sterilizing toothbrushes have been described in the prior art. One such self-sterilizing toothbrush is described by White et al., U.S. Pat. No. 2,216,333, and includes a combination of a water soluble salt (e.g., sodium carbonate) with an anti-microbial agent (e.g., sulfur). The two are fused to a solid hard body and attached to the head of the toothbrush at the base of the bristles. When exposed to water the sodium carbonate dissolves, forming an alkaline solution that in turn dissolves some sulfur, which kills bacteria.
Toothbrushes wear out with extended use. Breuer et al., U.S. Pat. No. 4,802,255, describe a toothbrush that includes filaments that release a dye, and thus change color, in response to increased use of the filament. The change in color provides a means for monitoring the degree of wear of the toothbrush.
Kent, U.S. Pat. No, 5,061,106, describes including capsules or microspheres in the tuft holes in which the bristles of a toothbrush are mounted. The capsules or microspheres include a disinfectant or medicant that is released during use. A dye may also be included in the structures. The dye also is released over time to enable the user to become aware of when the contents of the capsules are depleted.